diff --git a/requirements.txt b/requirements.txt
index 5b619b3..b950afe 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -8,7 +8,7 @@ itsdangerous==0.24
 Jinja2>=2.11.3
 langid==1.1.6
 MarkupSafe==0.23
-nltk==3.4.5
+nltk==3.6.6
 nose==1.3.7
 nose-watch==0.9.1
 numpy==1.11.0